Whiteboard is often used in work and life to make record or discussion. For example, in teaching and meeting, words, symbols and so on can be written on the whiteboard and can also be erased conveniently. However, the content written on the traditional whiteboard appears only once; it can't be stored and reproduced. Therefore, it is hard for the traditional whiteboard to satisfy the increasing application requirements of current digitized life and work.
Along with the development of electronic technology, an electronic whiteboard is used for teaching in school and for studying and discussing in a department. Such product can promptly convert the symbols written on the whiteboard into electronic signals, and transfers the electronic signals to a connected computer, then directly accomplishes editing or remote information commutation of printing, transmission, etc. via the computer. For the existing electronic whiteboard, due to its large induction area, it is impossible to manufacture, for example, etching and manufacturing the electromagnetic induction type of the printed circuit board, or the resistance-induction type frames like touch screens cannot be adopted as the induction frame because of high cost. Therefore, the ultrasonic wave transmission and reception between an input pen and an electronic whiteboard is widely used in electronic whiteboard controlling and operation. But the application of such products is limited due to the high cost and low accuracy.
In conclusion, the existing products have many disadvantages, such as: very low identification ratio, poor accuracy, high cost, and difficulty in manufacture, which limit wide application of such products.